The principles of gas discharge and of plasma chemistry are known and described for example in A. T. Bell "Fundamentals of Plasma Chemistry" ed. J. R. Hollahan and A. T. Bell, Wiley, N.Y. (1974).
Processes for the plasma treatment of wool are likewise known per se and described for example in the papers by A. E. Pavlath et al., Text. Res. J. 45(1975) p. 742, and W. Rakowski, Melliand Textilber. 10(1989) p. 780.
German Offenlegungsschrift DE-41-17-332-A1 describes a process for the plasma treatment of moving textile webs wherein, inter alia, dried wool fabrics are subjected to a direct current discharge in air at about 80 to 90 Pa.
German Offenlegungsschrift DE-43-39-427-A1 likewise describes a plasma treatment process for fabric webs, but it is additionally supplemented by a downstream ozone treatment. This process is used for cleaning and desizing a cloth so as to replace traditional liquid pretreatments of textile webs. Both processes concern the treatment of already woven or knitted fabrics or of other webs of material. The references do not concern the pretreatment of unspun fibres or raw wool.
Processes are also known for a low temperature plasma or corona discharge treatment of wool to improve the dyeing of the wool. For instance, European Offenlegungsschrift EP-0 548 013 A1 describes a process for dyeing wool level in the fibre and the piece by subjecting the dried wool to a low temperature plasma or corona discharge with a non-polymerizable gas and then dyeing it from an aqueous liquor free of levelling agent.
It has now been found that the plasma treatment does in practice bring about a certain improvement in dyeability. However, the textile processing industry is particularly interested in a reduction in the felting tendency of wool, especially of raw, or unprocessed, wool.
The felting of wool is customarily reduced by finishing the wool with applied auxiliaries.
However, processes are also known for the antifelt finishing of wool by means of a combination of plasma pretreatment and enzymatic aftertreatment. Such a process is described for example in German Offenlegungsschrift DE-43 44 428 A1.
The existing processes cited are ineffective or unsatisfactory with regard to the antifelt finishing of wool.
In addition, plasma treatment processes are handicapped by the presence of water, present in most wools up to a maximum proportion of 33% by weight or even up to 40% by weight in the case of alkali treatment.
The varying moisture content of the fibre is considered a disadvantage for these processes because the production throughput fluctuates as a result. For this reason, in the processes, the wool material is dried prior to the plasma treatment at the cost of additional complication and expense.
Plasma treatment in the presence of small amounts of water is otherwise only known from U.S. Pat. No. 5,344,462.